Hybrid Additive Manufacturing by Embedded Electrical Circuits Using 3-D Dispensing

In this study, a 3-D dispensing method for nonconductive and conductive adhesives is introduced that allows for direct electrical functionalization of the printed part during the printing process. The experimental work's focus lies on the analysis of the embedding of conductive tracks within nonconductive housings. Two different construction strategies have been analyzed for printing tracks in both xy - and z -directions. For all variants, initial feasibility tests were performed that successfully validated the general applicability of these techniques. As dissimilar materials are involved in the process, a micrograph analysis was used to investigate possible negative effects within the transitional areas. Although prototypical parts can be built easily with additive manufacturing methods, the lack of knowledge about the long-term robustness is often the limiting factor to end-use applications. Accelerated life tests in the form of thermal shock and humidity testing were performed to investigate this issue. The tests demonstrate good long-term behavior for two of four adhesives. The obtained results show that the proposed method and process variants are capable of producing electronically functional parts, provided a careful material selection has been performed. Furthermore, several design rules concerning the transitional area could be derived.